The business of contracts, from the owners' viewpoint, is what's the risk? So they get fined and a slap on the wrist, some have saved more than the fine by appealing to the player.
One thing to consider is that a large % of these players are not smart, not their fault, the smart sperm were poor swimmers, and the agent is only going to line out what is in his own best interest. This is not to say that they don't care about the player because some do but their job is to get the fattest commission for them and their company. And use that to get more clients.
Is it not fair for an owner to talk to his employee or potential employee about the salient factors of his city and team? Doesn't mean he can end run the agent and try to negotiate the player down but he can put forth some positives about joining or staying with his team to counter only the $ side that the agent is using. But in all fairness to the agent, he is hired to get the best possible deal for his client.
If you were an agent and felt you could get more for your client, would you not advise him to stand firm? The player can always take the last deal offered, they don't punish them by retracting the offer. The agent is there to make sure the player keeps his eyes on the prize.